1. Field of the Invention
The present invention relates to an image reproducing technique for carrying out image reproducing operations in accordance with the precedence of multiple types of jobs existing in parallel. More particularly, the present invention relates to job order coordination for a multi-function image reproducing system in accordance with the optimum order of job execution even after suspend of operations.
2. Description of Related Art
Use of so-called multi-function imaging apparatuses that can function as multiple imaging devices, such as a photocopier, a printer, a facsimile machine, etc. is spreading. Such a multi-function imaging apparatus is furnished with different types of applications, including a copy application, a printer application, a facsimile application, scanner application, etc., and it is capable of dealing with execution requests supplied individually from multiple applications The multi-function imaging apparatus is also capable of processing multiple imaging requests from multiple users.
In order to process multiple requests simultaneously generated from different applications, the multi-function imaging apparatus needs to have the ability to successively execute the jobs existing in parallel in accordance with the order of job precedence or the order of acceptance.
On the other hand, along with a variety of printing modes, demand for mass printing functions or flexible printing functions with a finishing process is increasing. In response to the demand, several types of paper-eject trays are provided to image reproducing apparatuses corresponding to different printing modes. For example, a shift tray (or a large-capacity tray) capable of receiving a massive amount of printed papers in the mass printing mode, or a finisher having a finishing function, such as stapling, in combination with a paper-eject tray, is furnished. In addition, a second or a third tray is also provided, which is suitably used to receive printed papers in the ordinary image reproducing mode or when receiving facsimile communications.
During the mass printing operation, paper ejection to a large-capacity tray may be temporarily suspended for the purpose of removing the paper piled on the tray. After removal of the paper, the apparatus is released from the suspension, and resumes the printing and paper-eject operations. With a large-capacity ejection tray, the tray position descends as the ejected paper is accumulated on the tray in order to receive the ejected paper at the appropriate position. Accordingly, the temporary suspension is not removed until the tray returns to the correct position for appropriately receiving newly ejected paper after the accumulated paper has been removed.
However, stopping all the operations regarding image reproduction during the suspension degrades the productivity of the image reproducing apparatus. To overcome this problem, JPA 2001-253625 discloses an image reproducing apparatus that continuously carries out a job scheduled for paper ejection to a tray other than the large-capacity tray during the suspension of paper ejection to the large-capacity tray.
The image reproducing apparatus disclosed in this publication has suspension instruction means that allow the user to suspend paper ejection to the large-capacity tray. When the user manipulates the suspension instruction means during the printing operation, currently implemented paper ejection to the large-capacity tray is suspended, and the apparatus does not accept further jobs that require paper ejection to this large-capacity tray until the suspension is removed. On the other hand, jobs that do not require paper ejection to the large-capacity tray are continuously accepted and executed.
Temporary suspension is also desired in multi-function imaging apparatuses, in which multiple types of job requests are supplied from different types of applications. For example, when a job having a higher priority is being implemented prior to other jobs requested from different applications, the user may wish to suspend paper ejection to a certain tray for the purpose of removing the paper piled on the tray.
However, a problem will occur if arrangement of temporary suspension (for example, suspension of paper ejection to a certain tray or suspension of other operations for the purpose of changing parameters) is applied to a conventional multi-function imaging apparatus. If the user instructs the multi-function imaging apparatus to suspend paper ejection to a certain tray under the situation where multiple jobs from different applications have been accepted, and if the apparatus is released from the suspension, then a job with a lower priority may be executed first before the currently suspended higher-priority job is resumed. This is because when the multi-function imaging apparatus is released from the suspension, the respective applications generate execution start requests for the already accepted jobs in order of restart of applications, and the jobs are executed in order of generation of the execution start requests.
For instance, paper ejection to the large-capacity tray may be temporarily suspended during the execution of a copy job requested from the copy application, which has a priority higher than a print job requested from the printer application. After the pile of photocopies is removed from the tray, the tray returns to the correct position and the suspension is removed. Then, each application resumes. If the printer application resumes first, it generates an execution request for the print job already accepted in the multi-function imaging apparatus. In this case, the print job is executed immediately after the removal of suspension, even if the higher-priority copy job has not been finished yet.
If this happens in the multi-function imaging apparatus, the order of job precedence changes between before and after the suspension. As a result, output result of a lower-priority job get mixed in the pile of paper of the currently executing higher-priority job. Thus, the paper eject order is mixed up. The user has to watch every time a suspension is removed to see whether printed paper of other jobs is mixed into the reproduced sheets of the target job.
The same problem occurs in an image reproducing apparatus, such as a color photocopier or a color printer, with a function of receiving multiple types of imaging jobs (or execution requests) in parallel. The present invention was conceived to overcome the above-described problem in the prior art technique, and it is an object of the present invention to provide an image reproducing method and apparatus that can prevent the order of job precedence from varying before and after suspension of imaging-relating operations, and that can start job execution in the appropriate order even after removal of the suspension.
It is also an object of the present invention to provide an image reproducing method and apparatus that can resume printing and paper ejection, while maintaining the order of job precedence without degrading productivity, when the image reproducing apparatus is released from suspension of paper ejection.
The present invention is applicable to multi-function image reproduction covering the functions of a photocopier, a printer, a facsimile machine, a scanner, etc. Therefore, it is still another object of the present invention to provide an image reproducing method and apparatus that can resume printing and paper-eject operations, while maintaining the order of job precedence throughout, before and after suspension, regardless of the types of applications installed in the apparatus.